OK - that's the Mint colour scheme so you'll need to install a
different theme that you like better, don't think you've much option
around the colour of that bar but you can try customising the theme.
Not sure where it is in Mint but try [ System / Preferences /
Appearance / Customise ]

BC> As for the border its the bar that is on top of for example
BC> Firefox. It is the Mint Green and is on the same row as the close
BC> X.